We will investigate the effects of hydroxychlorodiphenyl ethers (predioxins) on the mammalian erythrocyte, mitochondrial oxidative phosphorylation, and microsomal enzyme activity, particularly with regard to membrane effects of these chemicals. The acute toxicity in rats and mice will also be determined. These studies are aimed at elucidating the mechanism for the biochemical effects and toxicity of the hydroxychlorodiphenyl ethers, and at assessing the potential hazard of these compounds to man.